Automotive vehicle doors are almost invariably provided with a sliding window which can be raised to a position sealingly closing a window opening and which can be lowered to a position wherein the window is stored in a cavity within the vehicle door. The periphery of the window opening in a vehicle door is generally provided with a plurality of polymeric sealing elements having resilient elastomeric characteristics to allow for smooth movement of the window and to ensure sealing engagement between the window and that portion of the door frame defining the window opening, even after thousands of cycles between the open and closed positions over many years of service. The sealing elements surrounding the window opening generally include a header and pillar or side elements which typically have a substantially U-shaped portion into which the edges of the window are received, and a pair of opposing inner and outer beltline sealing elements which are attached to the door frame along the lower edge of the window opening. The header, pillar and beltline sealing elements are generally attached to a pinchweld flange or U-shaped channel formed by the sheet metal defining the door frame, with the door frame serving as a reinforcement for the sealing elements to stabilize or counter forces exerted by the window along its edges as it is being raised or lowered.
Below the beltline, within the door cavity or well, the window is typically guided by a pair of spaced parallel rails or glass runs. The belowbelt glass runs generally comprise an elastic U-shaped member of, for example, rubber which does not serve a sealing function, but instead provides a nonabrasive, low-friction guide liner which promotes smooth movement of the window as it is being raised or lowered. Typically, the edges of the door frame below the beltline are not in close proximity to the belowbelt glass runs and are therefore unavailable for providing reinforcing support to the elastic member or guide liner to stabilize or counter forces exerted by the window along its edges when it is being raised or lowered as is the case with the window sealing elements. Accordingly, conventional belowbelt guide means generally include a rigid retainer having a U-shaped cross section into which the guide liner is received. The rigid retainer is generally made of a tough, high modulus material such as steel and is rigidly fixed to the frame as by welding or mechanical fasteners. The rigid retainer supports the guide liner and acts to stabilize forces exerted onto the belowbelt glass run by the window especially when it is being raised or lowered.
In FIG. 3 of U.S. Pat. No. 4,098,134, a typical prior art belowbelt glass run 45 comprising an underlying steel support member having a U-shaped channel and an elastomeric liner received within the U-shaped channel is shown. Conventional belowbelt glass runs comprising a support member and separate guide liner are generally adequate for holding the glass on track with a smooth, consistent motion as the window is being raised or lowered in the door. Automobile and automotive component manufacturers are, however, continually endeavoring to provide high quality components which meet or exceed consumer expectations while simultaneously reducing manufacturing and assembly costs. Accordingly, a below-belt glass run design which is capable of smoothly guiding a window of a vehicle door and which incorporates a simpler design comprising fewer components, thereby reducing manufacturing and assembly costs, would be highly desirable.